A radio frequency (RF) duplexing device is a device that facilitates bi-directional communication (i.e., simultaneous reception and transmission) by a common antenna. In order to facilitate simultaneous reception and transmission by the antenna, the RF duplexing device operates at both an RF receive band of an RF receive signal and an RF transmission band of an RF transmission signal. One of the primary challenges of duplexing is that the RF transmission signal and the RF receive signal can interfere with one another. Furthermore, upstream RF circuitry for the RF transmission signal can distort the RF transmission signal, while downstream RF circuitry for the RF receive signal can also distort the RF transmission signal. So that the RF transmission signal and the RF receive signal can comply with spectral requirements, the RF duplexing device needs to provide adequate isolation between transmission channels and receive channels.
A typical RF duplexing device provides additional isolation by increasing impedances and/or providing a higher amount of attenuation between transmission and receive channels. However, this results in greater insertion losses and thereby reduces power efficiency performance of the RF duplexing device. As both power efficiency standards and spectral requirements become more demanding, better techniques are needed to provide greater isolation between transmission and receive channels.